Methods and system for maintaining data coherency in distributed data cache network

• US 9,952,968 B2
• Filed: 01/29/2010
• Issued: 04/24/2018
• Est. Priority Date: 01/29/2010
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company, Micro Focus Software, Inc. (Open Text Corporation)
• Original Assignee: Micro Focus Software, Inc. (Open Text Corporation)
• Inventors: Lowry, Lee Edward, Thurgood, Brent, Carter, Stephen R
• Primary Examiner(s): Savla, Arpan P.
• Application Number:
  US12/696,689
• Publication Number:
  US 20110191541A1
• Time in Patent Office: 3,007 Days
• CPC Class Codes: G06F 12/08 in hierarchically structured memory systems, e.g. virtual memory systems
• CPC Class Codes: G06F 12/0815 Cache consistency protocols
• CPC Class Codes: G06F 16/9574 of access to content, e.g. by caching
• CPC Class Codes: G06F 2212/264 Remote server
• CPC Class Codes: G06F 3/0481 based on specific properties of the displayed interaction object or a metaphor-based environment, e.g. interaction with desktop elements like windows or icons, or assisted by a cursor's changing behaviour or appearance
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: H04L 67/5682 Policies or rules for updating, deleting or replacing the stored data

Abstract

Techniques for distributed cache management are provided. A server having backend resource includes a global cache and a global cache agent. Individual clients each have client cache agents and client caches. When data items associated with the backend resources are added, modified, or deleted in the client caches, the client cache agents report the changes to the global cache agent. The global cache agent records the changes and notifies the other client cache agents to update a status of the changes within their client caches. When the changes are committed to the backend resource each of the statuses in each of the caches are updated accordingly.

Claims

1. A method implemented and residing within a computer-readable storage medium that is executed by one or more processors of a network to perform the method, comprising:

configuring a global cache on a server to manage state changes for data items that are cached in multiple network clients, the global cache is a centralized cache for the network and each client includes its own independent cache and the global cache acting as a reverse proxy for a backend resource on the server, the backend resource is a directory service, wherein the data items are just data items that have been changed since being flushed and once flushed the data items are no longer present in the global cache unless subsequently changed in one of the independent caches;

receiving notice from a first agent, which processes on a first client, the notice indicating a pending change to a particular data item was made within a first cache of the first client;

recording the pending change within the global cache when the pending change comports with a first policy;

enforcing the first policy to identify a mechanism having a second policy for one or more second agents for the one or more second agents to use the mechanism to resolve whether to accept or deny the pending change, the second policy defining whether to instruct the one or more second agents to;

use the second policy for resolution;

use the second policy in combination with a changing principal'"'"'s identity that made the pending change; and

request approval from a particular client principal, and interactively receiving acceptance or denial of the pending change from the one or more second agents by sending a request to the one or more second agents and sending the request as a particular mechanism defined in the first policy, and the particular mechanism is an Application Programming Interface call when the particular client principal is an automated service, and the particular mechanism is one of;

an instant message, a text message, and a dialogue box when the particular client principal is a particular user; and

pushing the pending change with the second policy to the one or more second agents from the global cache, each second agent processing on a different second client and each different second client having a second cache where the data items are being independently accessed, and directing each second client to repaginate its cache and resort its cache but maintain an unchanged view when the particular user is viewing its cache before the repagination and resorting are processed, and receiving a second change for the particular data item before committing the pending change and before flushing the global cache with the pending change when the second change is received, and also reporting the second change to the clients.

2. The method of claim 1 further comprising, committing the pending change to a backend resource having the data items and instructing the first agent and the one or more second agents to remove a pending status from the particular data item to indicate that the pending change has been committed.

3. The method of claim 1, wherein receiving the notice further includes determining in response to the first policy that the pending change is unauthorized and instructing the first agent to back out the pending change from the first cache on the first client.

4. The method of claim 1, wherein recording further includes maintaining the changing principal'"'"'s identity for a principal that made the pending change on the first client with the pending change for the particular data item in the global cache.

5. The method of claim 4, wherein pushing further includes providing the changing principal'"'"'s identity to each of the one or more second agents for retention in each of the one or more second caches.

6. The method of claim 5, wherein providing further includes:

receiving from a particular second agent a denial of the pending change along with a second principal identity;

evaluating a third policy using the second principal identity indicating that a second principal is authorized to issue the denial;

removing the pending change from the global cache; and

instructing the first agent and remaining ones of the second agents to back out the pending change.

7. The method of claim 1, wherein pushing further includes recoding the pending change in a log along with a date and time stamp, a first client identifier for the first client and a principal identifier for a principal of the first client that initiated the pending change.

8. A method implemented and residing within a computer-readable storage medium that is executed by one or more processors of a network to perform the method, comprising:

receiving a pending change for a data item from a global agent that manages a global cache for a server, wherein the global cache includes just data items that have been changed since being flushed and once flushed the data items are no longer present in the global cache unless subsequent changes are made, the pending change received with a policy to resolve whether to accept or deny the pending change, and the policy defining whether to instruct processing to;

use the policy for resolution;

use the policy in combination with a changing principal'"'"'s identity that made the pending change; and

request approval from a particular principal and wherein the global cache is a centralized cache on the server and acts as a reverse proxy for backend resources of the server, the global cache managing state changes for multiple data items existing on multiple independent caches for clients of the network, the backend resources are directory services, and receiving a request for the accepting or denying the pending change, the request including a particular mechanism defined in the policy, and the particular mechanism is an Application Programming Interface call when the particular principal is an automated service, and the particular mechanism is one of;

a text message, an instant message, and a dialogue box when the particular principal is a user;

determining whether to accept or deny the pending change for the data item and when accepted updating a client cache on a client with the pending change, the determining achieved by evaluating the policy; and

repaginating and re-sorting the client cache based on the pending change when the pending change is accepted, wherein a current view of the client cache being viewed by the user of the client cache remains stable and unchanged for the user during the repagination and/or re sorting, and receiving a second change to the data item before committing the pending change and before flushing the global cache with the pending change when the second change is received, and also reporting the second change to the clients.

9. The method of claim 8 further comprising, making the second change to a different data item in the client cache and reporting the second change to the global agent, the global agent records the second change and pushes the second change to one or more second clients for updates to one or more second caches of the second clients or the global agent receives pull requests from the one or more second clients for each of the one or more second clients to pull the second change to their one or more second caches.

10. The method of claim 8, further comprising, making the second change to the data item in the client cache and reporting the second change to the global agent, the global agent records the second change and pushes the second change to one or more second clients for updates to one or more second caches of the second clients or the global agent receives pull requests from the one or more second clients for each of the one or more second clients to pull the second change to their one or more second caches.

11. The method of claim 8, wherein determining further includes denying the pending change for the data item in response to evaluation of the policy and then instructing the global agent to back out the pending change from the global cache and instructing one or more second clients to back out the pending change for the data item in one or more second caches.

12. The method of claim 8, wherein determining further includes denying the pending change for the data item in response to evaluation of the policy and in view of the changing principal'"'"'s identity associated with the pending change, the changing principal'"'"'s identity indicating a principal that made the pending change and then instructing the global agent to back out the pending change from the global cache and further instruct one or more second clients to back out the pending change for the data item in one or more second caches.

13. A multiprocessor-implemented system, comprising:

a global cache agent implemented in a computer-readable medium and to process on a server; and

a plurality of client cache agents implemented in computer-readable media, each client cache agent to process on a client and manage a client cache;

the global cache agent is configured to manage pending state changes for data items associated with a backend resource of the server via a global cache, the backend resource is a directory service, wherein the global cache agent is further configured to synchronize pending changes to the data items received from each of the client cache agents by receiving the pending changes from those client cache agents originating the pending changes and pushing the pending changes to those client cache agents that did not originate the pending changes and pushing a first policy to identify a mechanism having a second policy for the client cache agents to use in resolving whether to accept or deny the pending changes, and interactively receiving acceptance or denial of the pending change from the client cache agents by sending a request to the client cache agents and sending the request as a particular mechanism defined in the first policy, and the particular mechanism is an Application Programming Interface call made to the one or more second agents, the second policy defining whether to instruct the client cache agents are to;

use the second policy for resolution;

use the second policy in combination with a changing principal'"'"'s identity that made the pending change; and

request approval from a particular client principal, wherein the global cache is a centralized cache for the network and each client includes its own independent cache and the global cache acting as a reverse proxy for a resource on the server, and client cache agent is to repaginate its cache and resort its cache but maintain an unchanged view when a particular user is viewing its cache before the repagination and resorting are processed, and the global cache agent configured to receiving a second change to a particular pending change for a particular data item before that particular pending change is committed and before flushing the global cache with the pending change when the second change is received, and also and reporting the second change to the client cache agents, and request the approval as one of;

a text message, an instant message, and a dialogue box when the particular client principal is the particular user, wherein the global cache includes just data items that have been changed since being flushed and once flushed the data items are no longer present in the global cache unless subsequently changed in one of the independent caches.

14. The system of claim 13, wherein the global cache agent is configured to enforce a third policy to determine whether to allow the pending changes.

15. The system of claim 13, wherein the global cache agent is configured to permit a particular client cache agent to reject a particular change to a particular data item and in response thereto instructs the other client cache agents to back out the particular change in their client caches.

16. The system of claim 13, wherein the client cache agents are configured to repaginate and/or re-sort their client caches when warranted by the pending changes and any current views of users for the client caches on the clients remain stable so the users do not lose positions or locations in their current views.